Gun barrel liner



March 21, 1961 J. c. R. KELLY, JR 2,975,677

GUN BARREL LINER Filed June 26, 1952 INVENTOR JOHN GR. KELLY, JR.

BY iza ATTORNEYS GUN BARREL LlNER Filed June 26, 1952, Ser. No. 295,635

4 Claims. (Cl. 89-16) This invention generally relates to gun barrel or gun tube liners, and more particularly to segmented liners for gun tubes, and the method of forming the same.

Because of the ditficulty of forming large one-piece gun liners embodying the requisite physical properties of ductility, strength, resistance to high temperatures, wear, and chemical erosion, and the added difficulty of boring such an elongate liner, it is customary in the art to assemble gun liners from a plurality of axially aligned sections or annular segments of a suitable material such as molybdenum or molybdenum alloyed with such metals as tungsten, cobalt, or nickel. Each annular segment is independently preformed and worked to provide the proper crystalline structure for the desired physical properties, and is thereafter keyed or otherwise connected to adjoining segments to form an integral unit. Of course in the manufacture of such liners from these annular segments, it is necessary that they be securely keyed together against axial or rotational displacement as may result from the passage of a fired projectile therethrough, and accordingly the art employs such expedients as interconncting pins and overlapping joints to interlock these members. However, this prior art segmented liner construction and assembly is costly and difiicult for the pin and overlapping joint construction necessitates extensive and exacting boring and machining of the segment surfaces, and in addition the assembly of these specially prepared segments requires proper alignment thereof. iFurther, units thus assembled have not been altogether satisfactory, for oftentimes these interlocking means fail to prevent the liner sections from being split, rotated, or physically displaced by the passage of a fired projectile therethrough, thereby necessitating repair or replacement of the liner.

The present invention proposes to correct these defects and simplify liner construction by providing a gun tube liner formed of a plurality of partially preformed and preworked annular segments secured together end to end in axial alignment and keyed in a novel manner to effectively prevent their splitting, rotating, or being otherwise displaced by the passage of a projectile therethrough. In addition a novel method is propsed for constructing this liner wherein the preformed sections are assembled together and thereafter handled as a unit in performing final forming and machining operations thereon, thereby eliminating some of the steps of prior methods and re placing them with simpler and less costly procedures, to enable both an improved product and a simplified, less costly, and improved method of making this product.

It is accordingly one object of this invention to provide an improved method of constructing a liner for gun tubes.

A further object of this invention is to provide an improved method of assembling a liner for gun tubes from a plurality of annular segments.

A further object of this invention is to provide an improved method of constructing a segmented gun tube liner wherein a plurality of partially preformed annular segments are clamped end to end, and thereafter handled as an integral unit in performing final forming and machining operations thereon.

A further object of this invention is to provide a liner for gun tubes, formed of a plurality of annular segments and having improved means for holding these segments together and against relative displacement.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Figs. 1-5 inclusive are isometric views of a preferred embodiment of the liner at chronological stages of its construction in accordance with the preferred process; and

Figs. 6, 7, and 8 are isometric views of proposed alternative embodiments of the liner annular segment construction.

Referring now to Figs. 1-5, in sequence, for a detailed consideration of one proposed gun liner formed in accordance with the present invention, and of a preferred process for constructing this liner, a plurality of sections or segments 10 (Fig. 1), preferably of molybdenum or suitable alloys thereof, are initially formed from stock worked as by plastic deformation until the desired physical properties of ductility, strength, and hardness are acquired. The segments are preferably axially bored individually in accordance with the type of gun to be constructed. Thereafter, they are placed on a steel mandrel or the like and clamped together by suitable means such as a nut and bolt closure 11 and 12 at one end, and a stop 13 at the opposite end, as illustrated in Fig. 2, to enable these segments to be handled together as a unit in subsequent operations. These clamped segments may then be externally machined as a unit to provide a plurality of upstanding ribs 15 (Fig. 3), or these ribs may have been initially formed on the segments individually before placement on the mandrel.

As the function of these upstanding ribs in the completed gun liner is to prevent rotation and translation of the segments in a gun barrel particularly when exposed to the forces of a projectile fired therethrough, the pattern formed by the ribs is selected to key them against movements of this kind, as may be more fully comprehended hereinafter.

Upon completion of the external machining operation forming the upstanding rib pattern v15 on the assembled segments 10, the assembly is thereafter placed within a cylindrical jacket 14 (Figs. 3 and 4), of soft steel, heat treatable steel, or other such deformable metal, whose length is coextensive with the axially clamped segments, and the entire unit is thereafter placed within a rubber pressure bag (not shown) similar to a type employed for hydrostatic pressing of metal powders into sintered metals and well-known in the art. The rubber bag and its contents are then subjected to a relatively large hydrostatic pressure, which is necessarily less than the elastic limit of the metal forming the annular segments, and in the preferred embodiment is of the order of 20,000 p.s.i. to 60,000 p.s.i., whereby the deformable jacket is compressed and forced to How about the surface of the segments, thereby firmly embedding the ribs 1'5 in the jacket as shown by Fig. 5. Finally, the substantially completed gun lining which now has a somewhat irregular outer surface is removed from the mandrel and centerless ground, surface ground, or otherwise machined to a suitable cylindrical form to thereby complete the liner construction, and enable its insertion into a primary carrier or gun barrel (not shown).

Thus, the upstanding ribs 15 when firmly embedded within deformable jacket or shroud 14 lock the segmentS teachings.

" translational movements within the shroud, thereby eliminating the need for pins and lap joints formerly employed for-performing thesefunctions. :In addition, as is apparent, should the upstanding ribs be formedon the individual segments before: assembly .on the mandrel,

there would nevertheless be no need for rotating these segments to bring their ribs into a precisely alignedpattern, for the ribs on each segment perform their keying functions independently of the others. This latter feature is significant in view of the prior art devices wherein interlocking means between segments necessitate a preeise alignment therebetween, thereby increasing the difficulty and cost of assembling the liner.

Figs. 6, 7, and 8illustrate alternative upstanding rib patterns 16, 1'7, and 1-8 machined on the segments 10 I which also possess the attribute of keying the segments against rotation and translation when embedded in a shroud, and it is apparent that. many rib-configurations may be readily designed for performing the functions of those herein illustratively presented.

Obviously many modifications and variations of the present invention are possible in the light of the above It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. The process of constructing a gun barrel liner com tubular jacket of deformable metal, deforming said tubular jacket onto said assembled segments under pressure to completely embed said ribs into a substantially homogeneous mass with said jacket and subsequently removing said mandrel.

act

2. The process of constructing a gun barrel liner comprising the steps of removably holding a plurality of annular metallic segments end' to end to form a unit, forming upstanding integral patterns of ribs extending generally longitudinally and annularly along the periphery thereof, encasing the machined unit within a single jacket of deformable metal, a'ndcompletely embedding said ribs by compression fitting said jacket onto said unit.

3. Theprocess of constructing a gun barrel liner comprising the steps of assembling a plurality of annular molybdenum segments axially on a mandrel, axially compressing said segments' to hold them in fixed position relative to one another,"forming, a plurality of mutually cooperative patterns oftintegral longitudinally and peripherally extending upstanding ribs only along the periphery of said segments, encasing the assembled and formed segments in a single tubular jacket of deformable metal, and deforming said tube to completely embed said translation thereby.

References Cited in the file of this patent UNITED STATES PATENTS Butler Jan. 25, 1876 Mannesmann Dec. 15, 1891 to extend generally longitudinally and peripherally along 

